The need for secure delivery is ony one of the risks of selling an item of this value.

Have you consdered the possibility that a buyer might claim some defect, and then return a different and damaged copy of this record - or a different record altogether? If so, how confident are you that eBay would find in your favour, and not the buyer's?

I'm not suggesting answers, just that these are questions you should ask yourself. Personally, I would not sell anything of such value here.